released photos. 10:30, the brothers tried to rob a 7-eleven store near the massachusetts institute of technology. then news a police officer was attacked. sean collier,26 years old, was shot as he s in his car. he died soon after. the brothers hijacked a car, and the chase that followed ended in watertown, 10 miles from boston. on the usually quiet suburban street, there was a fierce firefight, captured on mobile phones. the police were taking no chances. the innocent owner of the hijacked car was for a time treated as a suspect. tamerlan tsarnaev was fatally wounded. he died in hospital. >> the closed in around one guy. they got in position. >> w >> they were screaming at him. they all had their guns out. he was at the point where he was like this. finally, by the time the car came over, he finally laid down to go back on the ground, and that was said. >> the whole town has become a crime scene. the younger brother who escaped the shootout. >> you should be considered armed and dangerous and a threat to anybody he might approach. there is a 20-block perimeter around the location the chief is ta